JPH0221501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an absorption heat pump ( (hereinafter simply referred to as an absorption heat pump).

In general, a refrigerator has a cooling side and a heat radiation side.When the cooling side is used, it is called a refrigerator, and when the heat radiation side is used, it is called a heat pump.Most heat pumps, regardless of compression type or absorption type, into such a concept.

However, the absorption heat pump of the present invention is an absorption machine exclusively for heat pumps, which is different from the above concept.
A heat pump that uses low-temperature heat to evaporate refrigerant and extracts high-temperature hot water using the absorption heat generated when the refrigerant vapor is adsorbed by an absorption liquid.
That is, the present invention relates to an absorption heat pump of a type in which the refrigerant absorption temperature is higher than the refrigerant generation temperature, and the refrigerant evaporation temperature is higher than its condensation temperature.

The figure shows an example of such an absorption heat pump, in which an evaporator 2 and an absorber 3 are housed in an upper body 1, a generator 5 and a condenser 6 are housed in a lower body 4, and a refrigerant pump 7 is housed in these bodies. The evaporator 2 has a liquid refrigerant reservoir 13 and a liquid refrigerant connected to the evaporator 2 through a refrigerant pipe 8 having a liquid refrigerant, an absorption liquid pipe 10 having an absorption liquid pump 9, an absorption liquid return pipe 11, a heat exchanger 12, etc. A refrigerant circulation pump 14 is disposed to spray from the upper part of the evaporator 2, and the generator 5 and the evaporator 2 are each supplied with low-temperature heat source fluids (hereinafter referred to as low-temperature heat sources) such as waste hot water and waste steam, and absorb them. The heat supply heat exchangers 15 and 16 provide heat to the heat pump system, the condenser 6 has a built-in cooler 17 that cools and liquefies the refrigerant vaporized by the generator 5, and the hot water heat exchanger of the absorber 3 Hot water for hot water supply or heating can be taken out from 18.

For example, when using lithium bromide as the absorption liquid, water as the refrigerant, waste steam at about 90°C as the low-temperature heat source, and water C at around 30°C as the cooling water, the following diagram will appear as shown in the Duering diagram in Figure 2. Hot water H heated to 130°C is obtained from the hot water heat exchanger 18.

Therefore, since the absorption liquid of such absorption heat pumps is operated at a higher concentration than that of conventional absorption heat pumps, it is necessary to ensure that the absorption liquid is diluted when stopping heat pump operation. be. In addition, in conventional absorption heat pumps, operation is normally controlled by controlling the flow rate of the heat source fluid, but when using factory waste heat such as waste steam as the heat source, control of the heat source is the primary method. In some cases, such a control method cannot be used because it would cause damage to the factory, and the concentration of the absorption liquid circulating in the absorption heat pump may change depending on other conditions, causing the temperature of the hot water taken out to fluctuate. Otherwise, there was a risk that the absorption liquid would crystallize, making it impossible to operate the absorption heat pump.

The present invention was created in view of these points, and is aimed at stabilizing an absorption heat pump that uses waste steam or waste hot water as a low-temperature heat source and uses seawater or industrial water as cooling water to generate high-temperature level hot water or steam. The heat pump has a control mechanism that keeps the liquid temperature (or pressure) in the condenser almost constant during steady operation, and increases the liquid temperature in the condenser when the operation is stopped. It was designed to be attached.

In the figure, 19 is a temperature sensor 20 of the refrigerant reservoir 21 in the condenser, a sensor 22 of the outlet temperature of the cooling water that cools the condenser 6, or a sensor 2 of the pressure in the condenser.
A controller 24 which uses one of the above or a combination of these data as an input signal, is controlled by the controller 19.
This is a control valve that controls the amount of water to the cooler 17, and the controller 19 throttles the valve 24 when the temperature (or pressure) in the condenser or the temperature of the cooling water is decreasing, and when either of these is It has a mechanism that controls to open the valve 24 when the temperature tends to rise above the set value.

In this type of absorption heat pump, the amount of refrigerant generated from the absorption liquid in the generator 5 and the concentration of the absorption liquid supplied to the absorber 3 are
If the temperature of the low-temperature heat source supplied to the evaporator 2 is constant, the temperature of the cooling water in the condenser 6 is almost uniquely determined, so the temperature of the cooling water (for example, natural water such as seawater or groundwater) varies depending on the season. When the temperature of the absorption heat fluctuates, when the opening degree of the control valve 24 is adjusted by the controller 19 as described above, the temperature of the hot water taken out from the absorption heat pump is kept constant, and the absorption heat pump can be operated stably.

That is, when the low-temperature heat source is supplied to the evaporator 2 and the generator 5 at a constant temperature, when the control valve 24 is opened to increase the amount of cooling water, the condensation temperature decreases,
The amount of refrigerant generated from the absorption liquid in the generator 5 increases, increasing the amount of refrigerant separated into the condenser 6 and increasing the concentration of the absorption liquid. By controlling the temperature (pressure) inside the condenser 6, such as by reducing the amount of refrigerant generated and lowering the concentration of the absorption liquid, the concentration of the absorption liquid can be stabilized and the temperature of the hot water taken out can be kept constant.

Conversely, when a low temperature heat source with a changed temperature level is supplied to the generator 5 and the evaporator 2,
If the set value determined by this low temperature heat source water temperature is calculated by the controller 19 (or given from the outside) and the liquid temperature in the condenser is maintained at the new set value, the temperature level of the low temperature heat source will change. This makes it possible to operate an absorption heat pump that can take out hot water at a stable temperature.

Next, when trying to stop the absorption heat pump, upon receiving the stop signal, the controller 19 first fully closes the control valve 24, cuts off the flow of cooling water, and sets the liquid temperature in the condenser. It operates to raise the value higher than the value. Due to this operation, when the flow of cooling water to the condenser 6 is stopped, the refrigerant condensation in the condenser 6 is stopped, and the concentration of the absorption liquid (gasification separation of the refrigerant) in the generator 5 is also stopped. If the supply of the heat source fluid (low-temperature heat source) is stopped in this state, the operation of the absorption heat pump will be stopped with the concentration of the absorption fluid diluted, and the absorption fluid will be operated in a state where the concentration is relatively high and close to the crystal line. The operation of this type of heat pump can be stopped safely, that is, the operation can be stopped without the risk of crystallization of the absorption liquid during the stoppage of operation, which will cause problems when restarting the heat pump.

In addition, this type of operation control is not only applicable to stopping normal operation, but also to detect abnormal conditions such as an increase in pressure inside the absorption heat pump, an abnormal drop in cooling water temperature, or an excessive increase in absorption liquid concentration. When the water is supplied from the sensor, the cooling water control valve is similarly closed and the operation of the absorption heat pump is stopped after the temperature of the liquid in the condenser is raised above the set value.

As described above, in the present invention, in an absorption heat pump in which the temperature at which the absorption liquid absorbs the refrigerant is higher than the temperature at which the refrigerant is generated from the absorption liquid, and the evaporation temperature of the refrigerant is set higher than the condensation temperature of the refrigerant, A control mechanism is installed to control the cooling water temperature to maintain the liquid temperature in the condenser at the set value during operation, and to reduce the amount of cooling water to raise the liquid temperature in the condenser when the operation is stopped. This has the effect of maintaining the temperature of the hot water taken out at a constant temperature without the risk of crystallization of the absorbing liquid, while also allowing safe operation shutdown.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a device showing an embodiment of an absorption heat pump according to the present invention, and FIG. 2 is a Duering diagram for explaining the operation. 2...evaporator, 3...absorber, 5...generator,
6... Condenser, 19... Controller, 24... Control valve.

Claims (1)

[Claims] 1 Supply heat source fluid to the evaporator and generator while circulating cooling water to the condenser, and take out hot water at a temperature higher than the temperature level of the heat source fluid from the absorber. In absorption heat pumps that are airtightly connected with refrigerant pipes and absorption liquid pipes, the temperature of the liquid in the condenser is maintained at the set value during steady operation of the heat pump, and the temperature of the liquid in the condenser is increased when the operation is stopped. An absorption heat pump characterized by being equipped with a control mechanism.